Which of the following can be used to select the entire document ?

Word processors and most other software follow a standard set of keyboard shortcuts to speed up common actions. The shortcut used to highlight every piece of content in the active document at once, so it can be copied, deleted, or formatted in a single step, is formed by holding the Control key and pressing the letter A, which stands for "select All."

The other combinations listed perform unrelated actions. Holding Control and pressing K is commonly used to insert a hyperlink into a document, not to select text. Holding Shift and pressing A simply types a capital "A" when Caps Lock or Shift is used for a single letter; it has no special selection function. Holding Alt and pressing F5 is not a recognised standard shortcut in mainstream word processors and does not perform document selection.

A useful memory aid is that the letter chosen for a shortcut often matches the first letter of the action it performs: A for "Select All," C for "Copy," V for "Paste," and so on, which makes Ctrl + A the logical shortcut for selecting an entire document.